Temperature and pressure responsive filler cap



Nov. 8, 1966 A s MaOLENNAN 3,284,004

TEMPERATURE AND PRESSURE RESPONSIVE FILLER CAP Filed Nov. 18, 1964 SOLDER TENSION SOLD ER SOLDER TENSION SPRING 2 SOLDER ALASTAIR 5. MAC LENNAN INVENTOR.

A TTOR/VEVS United States Patent ()flhce 3,284,4 Patented Nov. 8, 1966 3,284,004 TEMPERATURE AND PRESSURE RESPONSIVE FILLER CAP Alastair S. MacLennan, Farmington, Mich, assignor to Ford Motor Company, Deal-born, Mich., a corporation of Delaware Filed Nov. 18, 1964, Ser. No. 412,175 4 Claims. (Cl. 236-92) This invention relates to a filler cap for the liquid cooling system of an internal combustion engine and more particularly to a filler cap embodying a temperature and pressure responsive valve means.

It is common practice to pressurize the liquid cooling system of an internal combustion engine to increase the boiling point of the liquid coolant. The increased boiling point permits engine operation at higher temperatures without a loss of coolant through boiling. The cooling system pressurization is normally obtained by providing a pressure responsive valve means in the filler cap of the cooling system. The pressure responsive valve means vents the cooling system to atmosphere when the coolant pressure exceeds the desired pressure.

Although it is advantageous to operate a cooling sys tem at an elevated pressure, the increased pressure places a higher stress on the various cooling system components such as the hoses, radiator core and radiator solder joints, The elevated cooling system pressure is normally encountered with the conventional filler cap embodying a pressure responsive valve at most times when the engines is operating. The increased pressurization of the cooling system is not required, however, except when coolant temperature approaches the boiling point at atmospheric pres sure.

It is therefore a principal object of this invention to provide a filler ca embodying a pressure responsive valve member that is additionally sensitive to the coolant temperature.

A liquid cooling system for an internal combustion engine embodying this invention includes a filler neck through which liquid coolant may be added to the system. A filler cap is detachably received on the filler neck for closing the system. Valve means are carried by the filler cap for pressurizing the cooling system. The valve means includes temperature responsive means for varying the pressurization of the system in response to changes in the coolant temperature.

Other objects and advantages of thisinvention will become more apparent as this description proceeds, particularly when considered in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a cross sectional view of a liquid cooling system for an internal combustion engine embodying this invention.

FIGURE 2 is a cross sectional view in part similar to FIGURE 1, showing a diflerent stage of operation.

Referring now in detail to the drawings, the upper wall of an expansion tank may be a radiator header tank if a vertical flow radiator is used or may be a separate expansion tank if a cross flow radiator is employed. A circular aperture 12 is formed in the upper wall 11. A generally cylindrical sheet metal filler neck 13 is positioned above the upper wall 11 around the aperture 12. The filler neck 13 has a flange portion that encircles the aperture 12 and engages both the upper and lower surfaces of the upper wall 11. The flange 14 may be welded or otherwise sealed around the periphery of the aperture 12 to prevent fluid leakage at this joint.

A filler cap, indicated generally by the reference numeral 15, is threaded onto an out-turned flange 16 formed at the upper end of the tiller neck 13. The connection between the filler cap 15 and the flange 16.may be of any known type. A cup-shaped sheet metal member 17 has an out-turned flange 18 that is welded, as at 19 around its periphery to the lower side of a horizontally extending part 21 of the filler cap 15.

A circular valve plate 22 is carried by the filler cap assembly 15. The valve plate 22 may be provided with an annular gasket 23 that is adapted to engage a horizontally extending surface 24 of the flange 14 around the periphery of a filler mouth 25 that is formed by the flange 14 of the filler neck 13. When the valve plate 22 and the gasket 23 engage the surface 24, the cooling system will be closed from the atmosphere. When the valve plate 22 and gasket 23 are axially spaced from the surface 24, the cooling system will be open to the atmosphere through a pressure relief vent 26 that is formed in the filler neck 13 between the flanges 16 and 14.

The valve plate 22 carries a temperature responsive device, indicated generally by the reference numeral 27. The temperature responsive device 27 may employ a wax pellet or some other temperature responsive element for operation in response to temperature variations. The exact construction of the temperaure responsive device 27 does not form a part of this invention, but it must have first and second relatively movable parts 28 and 29. In the illustrated embodiment, the first part 28 comprises a cylinder that holds some form of thermally expansible element such as a wax pellet and the part 29 comprises a rod that is adapted to move into and out of the cylinder 28 in response to temperature variations.

A disc 31 is afiixed to the upper end of the rod 29 by an overturned portion 32 ofthe rod 29. The disc 31 is received coaxially within the cup-shaped member 17 and the rod 29 extends through a central aperture 33 formed in the lower surface of the cup-shaped member 17. One end of coil spring 34 that is coaxially received within the cup-shaped member 17 engages the upper surface of the disc 31. The other end of the coil spring 34 engages the lower surface of the horizontal filler cap part 21 It should be readily apparent that as long as the gasket 23 engages the surface 24 and precludes communication between the cooling system and the atmosphere through the vent passage 26, the coolant system pressure will increase as the coolant temperature increases. The coil spring 34 which bears against the filler cap part 21 and the disc 31 will preclude movement of the gasket 23 away from the surface 24. When the coolant system pressure acting on the surface of the valve plate 22 exceeds the preload of the coil spring 34, the gasket 23 will move away from the surface 24 and permit venting of the cooling system until the pressure again decreases. Since the disc 31, which forms the reaction member for the coil spring 34 is connected to the rod 29 of the thermally responsive device 27, the preload of the spring 34 Will be dependent upon the relative positions of the rod 29 and the cylinder 28. The rod 29 will move axially out of the cylinder 28 as the temperature of the coolant increases. This has the effect of increasing the pressurization of the coling system as the coolant temperature increases.

Referring to FIGURE 1, the low temperature position of the various parts is shown. The rod 29 will have moved axially into the cylinder 28 until the disc 31 abuts the lower surface of the cup-shaped member 17. This engagement limits the expansion of the coil spring 34. It is desirable to preclude engagement of the gasket 23 with the surface 24 at low temperatures when the engine is not operating to guard against the generation of subatmospheric pressures within the cooling system. The valve plate 22 may be unseated by properly selecting the stroke of the rod 29 and the distance between the lower 3 surface of the cup-shaped member 17 and the surface 24 so that the valve plate 22 will be lifted oil of its seat at the desired temperature. Alternatively, a coil tension spring 35 may be affixed to the disc 31 and to the valve plate 22. The light tension exerted by the spring 35 will responsive device 27 causes the rod 29 to move axially out of the cylinder 28 (FIGURE 2). This movement of the rod 29 urges the valve plate and the gasket 23 into engagement with the surface 24 where it will serve as a reaction member for the temperature responsive device 27. This disc 31 will then be moved upwardly along with the rod 29 to compress the coil spring 34. The degree of compression will be dependent upon the temperature of the temperature responsive device 27 and the temperature of the coolant which it senses. Since both the coil spring 34 and the temperature responsive device 27 are linear devices, the amount of preload on the coil spring 34 will be directly proportional to the increase in temperature.

Before the valve plate can be urged away from engagement with the surface 24, the cooling system, the pressure acting on the valve plate 22 must exceed preload in the coil spring 34. The pressurization of the cooling system thus increases progressively as the temperature of the coolant increases. This is most desirable since the pressurization of the cooling system will increase as the temperature of the coolant approaches its boiling point. The increased pressurization will, of course, increase the boiling point of the coolant. The maximum degree of pressurization may be limited by appropriately selecting the stroke of the piston rod 29 and the rate of the coil spring 34.

It is to be understood that this invention is not limited to the exact construction shown and described, but that various changes and modifications may be made without departing spirit and scope of the invention, as defined by the appended claims.

I claim:

1. A liquid cooling system for an internal combustion engine including a filter neck through which liquid coolant may be added to said system, a filler cap detachably received on said filler neck for closing said system, a pressure responsive valve member carried by said filler cap for venting said cooling system to the atmosphere, biasing means urging said valve member to its closed position, stop means limiting maximum movement of said biasing means to establish a preload thereon, and temperature r'esponsive means for alternating the preload upon said biasing means for increasing pressure required to open said valve means in response to increases in the coolant temperature, said temperature responsive means being located on the coolant side of said valve member, said stop means being capable of preventing said biasing means from moving said valve member to its closed position at temperatures below a preselected value.

2. A liquid cooling system for an internal combustion engine including a filter neck having a mouth through which liquid coolant may be added to said system, a filler cap dctachably received on said filler neck for closing said system, a valve member carried by said filler cap and adapted to engage the mouth of said filler neck for closing said system, an atmospheric vent formed in said filler neck above said mouth, biasing means for urging said valve member into engagement with said mouth for precluding communication between said cooling system and said vent, stop means limiting maximum movement of said biasing means to establish a preload thereon, and temperature responsive means for preloading said biasing means to increase the pressure required to open said valve member in response to increases in coolant temperature, said temperature responsive means being located on the coolant side of said valve member said stop means being capable of preventing said biasing means from moving said valve member to its closed position at temperatures below a preselected value.

3. A liquid cooling system for an internal combustion engine including a filter neck defining a mouth through which liquid coolant may be added to said sysstem, a filler cap detachably received upon said filler neck, a valve member carried by said filler cap and adapted to engage said mouth for closing said system, biasing means in engagement with said filler cap, stop means limiting maximum movement of said biasing means to establish a preload thereon, temperature responsive means having a first portion afiixed to said valve member and a second portion aifixed to said biasing means, said portions being relatively movable upon changes in the temperature of said temperature responsive means for increasing the preload upon said biasing means in response to temperature variations for altering the pressurization of said cooling system, said temperature responsive means being located on the coolant side of said valve member, said stop means being capable of preventing said biasing means from moving said valve member to its closed position at temperatures below a preselected value.

4. A liquid cooling system for an internal combustion engine including a filler neck defining a mouth through which liquid coolant may be added to said system, filler cap detachably received on said filler neck, cool spring means in engagement at one of its ends with said filler cap, stop means limiting maximum movement of said coil spring means to establish a preload thereon, a movable valve member adapted to engage said mouth for closing said cooling system, vent means formed in said filler neck for communication of said cooling system with atmosphere when said valve means is not in engagement with said mouth, and temperature responsive means interconnecting the other end of said coil spring means with said valve member for resisting movement of said valve member from its closed to an open position, said temperature responsive means including a first portion aihxed to said valve member and a second portion in engagement with said other end of said coil spring means, said portions being relatively movable in response to temperature variations for increasing the preload upon said coil spring means upon increases in the coolant temperature, said temperature responsive means being located on the coolant side of said valve member said stop means being capable of preventing said coil spring means from moving said valve member to its closed position at temperatures below a preselected value.

References Cited by the Examiner UNITED STATES PATENTS 2,290,059 7/ 1942 Martin-Hurst 23692 2,333,993 11/1943 Frailing 23661 2,396,138 3/1946 Vernet 73-358 2,516,390 7/1950 Jensen 23692 X 2,535,974 12/1950 Watkins 23692 2,574,254 11/1951 Eshbaugh et al 23692 X ALDEN D. STEWART, Primary Examiner. 

1. A LIQUID COOLING SYSTEM FOR AN INTERNAL COMBUSTION ENGINE INCLUDING A FILTER NECK THROUGH WHICH LIQUID COOLANT MAY BE ADDED TO SAID SYSTEM, A FILLER CAP DETACHABLY RECEIVED ON SAID FILTER NECK FOR CLOSING SAID SYSTEM, A PRESSURE RESPONSIVE VALVE MEMBER CARRIED BY SAID FILLER CAP FOR VENTING SAID COOLING SYSTEM TO THE ATMOSPHERE, BIASING MEANS URGING SAID VALVE MEMBER TO ITS CLOSED POSITION, STOP MEANS LIMITING MAXIMUM MOVEMENT OF SAID HOUSING MEANS TO ESTABLISH A PERIOD THEREON, AND TEMPERATURE RESPONSIVE MEANS FOR ALTERNATING THE PRELOAD, UPON SAID BIASING MEANS FOR INCREASING PRESSURE REQUIRED TO OPEN SAID VALVE MEANS FOR INCREASING PRESSURE REQUIRED TO OPEN SAID VALVE MEANS IN RESPONSE TO INCREASES IN THE COOLANT TEMPERATURE, SAID TEMPERATURE RESPONSIVE MEANS BEING LOCATED BEING CAPABLE OF PREVENTING SAID BIASING MEANS FROM MOVING SAID VALVE MEMBER TO ITS CLOSED POSITION AT TEMPERATURES BELOW A PRESELECTED VALUE. 